DESCRIPTION: African Americans have a much greater risk of type 2 diabetes compared to Caucasians in the United States. Similarly, recent evidence has emerged that fitness level, a major risk factor for type 2 diabetes also tends to be lower in African Americans. Many scientific studies have shown that exercise training has a beneficial impact on fitness levels and a variety of other type 2 diabetes risk factors such as the reduction of glucose/insulin levels, and body fat Importantly, studies performed in mostly Caucasian populations suggest that exercise training at a vigorous intensity may promote greater improvements in type 2 diabetes risk factors compared to moderate intensity exercise, which may suggest that it has greater promise in reducing type 2 diabetes risk. However, few exercise training studies compare the health benefits of different exercise training programs (such as exercise intensity) in African Americans, which is clinically important due to their greater type 2 diabetes risk, and that fact that they are less likely to meet public health recommendations for physical activity compared to their Caucasian counterparts. The goal of proposed study is to evaluate the effects of 6 months of moderate versus vigorous exercise training in obese African Americans. The study will focus on the change in fitness levels, however, we will also collect information on the change in insulin sensitivity, skeletal muscle markers (associated with fitness or insulin sensitivity), body fat levels, quality of life, and enjoyment of exercise. This study will provide valuable information on what type of exercise training will offer the greatest improvement in T2DM risk factors in African Americans and potentially the prevention of type 2 diabetes.